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Auswahl der wissenschaftlichen Literatur zum Thema „Cracking of castings“
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Zeitschriftenartikel zum Thema "Cracking of castings"
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Eperješi, Š., M. Matvija, ľ. Eperješi und M. Vojtko. „Evaluation of Cracking Causes of AlSi5Cu3 Alloy Castings“. Archives of Metallurgy and Materials 59, Nr. 3 (28.10.2014): 1089–92. http://dx.doi.org/10.2478/amm-2014-0187.
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Abstract Recently, the castings made from aluminum-silicon alloys by pressure die casting are increasingly used in the automotive industry. In practice, on these castings are high demands, mainly demands on quality of their structure, operating life and safety ensuring of their utilization. The AlSi5Cu3 alloy castings are widely used for production of car components. After the prescribed tests, the cracks and low mechanical properties have been identified for several castings of this alloy, which were produced by low pressure casting into a metal mould and subsequent they were heat treated. Therefore, analyses of the castings were realized to determine the causes of these defects. Evaluation of structure of the AlSi5Cu3 alloy and causes of failure were the subjects of investigation presented in this article.
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Zeng, Yi Dan, Li Tong He und Jin Zhang. „Numerical Simulation of Casting Deformation and Stress of A356 Aluminum Alloy Thin-Walled Frame Casting“. Materials Science Forum 1033 (Juni 2021): 24–30. http://dx.doi.org/10.4028/www.scientific.net/msf.1033.24.
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One of the main reasons for the scrap of cast thin-wall frame aluminum alloy castings is deformation and cracking. It is an effective method for solving the problem by predicting the distribution of casting stress, clarifying the size of the deformation and the location of the crack, and taking necessary measures in the process. This paper uses the ProCAST software to simulate the thermal stress coupling of A356 thin-walled frame castings, analyzes the influence of pouring temperature, pouring speed and mold temperature on the stress field distribution of castings, predicts the hot cracking trend and deformation, and optimizes Casting process..
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Svobodová, Jaroslava, Štefan Michna und Iryna Hren. „Fractographic Analysis of Castings from Al-Si Alloy Produced by Low-Pressure Casting“. Materials Science Forum 994 (Mai 2020): 3–10. http://dx.doi.org/10.4028/www.scientific.net/msf.994.3.
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The article deals with the use of newly developed hypoeutectic silumin type AlSi9NiCuMg0.5 in manufacturing practice. This type of silumin has been produced and patented by a team of workers at the Faculty of Mechanical Engineering at the University of J. E. Purkyně in Ústí nad Labem, Czech Republic. This alloy was developed and tested directly for the technical practice where the special mechanical and technological properties of the alloy were required [1]. The experiment, which is presented in this paper, focuses on the cause of the castings cracking in operating conditions. When the material was put into practice, castings were produced and subsequently used for breaking and cracking across the entire casting section. AlSi9NiCuMg0.5 alloy castings were manufactured using low-pressure technology. The research is focused on the observation of the fracture surface, identification of microstructure of AlSi9NiCuMg0.5 alloy casting and determination of the chemical composition of structural components on the surface of fracture by EDS analysis. Fractional field research has measured the chemical composition and it has been compared with the required declared alloy. Increased iron content and associated intermetallic phases were identified in the alloy. Evaluating of the obtained results can identify the cause of the premature cracking of the castings made from the newly developed hypoeutectic silumin.
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Stradomski, Z., S. Stachura und G. Stradomski. „Fracture Mechanisms in Steel Castings“. Archives of Foundry Engineering 13, Nr. 3 (01.09.2013): 88–91. http://dx.doi.org/10.2478/afe-2013-0066.
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Abstract The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.
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Adamiec, Janusz. „The Assessment of Impact of Construction Factors on Weldability of MSRB Alloy“. Materials Science Forum 690 (Juni 2011): 37–40. http://dx.doi.org/10.4028/www.scientific.net/msf.690.37.
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The purpose of the work was to assess the impact of construction factors on weldability of MSRB alloy. One conducted transvarestraint test, which allowed to assess welds' susceptibility to cracking under the conditions of forced strain of the casting, Fisco test which simulates welding under the conditions of strong stiffening of the weld, as well as Houldcroft test simulating variable strain of the weld. One concluded that the strain of castings is characteristic of the process of pad welding and welding. Assessment of susceptibility of MSRB alloy to cracking under the conditions of forced strain allows to determine the width of the high-temperature brittleness range (HTBR), critical strain speed of the weld CSS and critical temperature strain intensity CST. These parameters are the criteria of hot cracking of welds from MSRB alloy, therefore, they are indicators of the assessment of the alloy's weldability. Castings from MSRB alloys with constant rigidity should be classified as easily weldable. On the other hand, variable rigidity of the casting, resulting from e.g. diverse thickness of the walls, causes significant increase in the alloy's susceptibility to hot cracking.
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Tang, Zheng Lian, und Xin Ping Zhang. „Effect of Rare Earth on 30CrMnSi Steel Investment Castings Cracking“. Advanced Materials Research 160-162 (November 2010): 692–97. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.692.
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Through adding different amounts of rare earth into the crack sensitive 30CrMnSi steel samples used in investment casting, the cracking tendency of the steel was evaluated and the optimum amount of rare earth addition was obtained. The results show that the cracking susceptibility decreases with the increase of the amount of rare earth added. The cracking susceptibility was lowest at the addition amount of rare earth ferrosilicon alloy being 450g per 50kg of 30CrMnSi steel, while increasing again thereafter with the addition amount up to 600g. It was revealed that the addition of rare earth with an appropriate amount can refine grains, reduce sulfur content, change the volume fraction and size of inclusions as well as improve their distribution, reduce or eliminate ferrite network in castings, and improve the hardness of the matrix, thus finally reduce the cracking susceptibility of the steel.
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Cao, G., und S. Kou. „Hot Cracking Susceptibility of Ternary Mg-Al-Ca Alloys“. Advanced Materials Research 15-17 (Februar 2006): 501–6. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.501.
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Hot cracking of ternary Mg-Al-Ca alloys in permanent mold casting was studied. The alloys are the base of some potential creep-resistant Mg alloys. The Mg-xAl-yCa alloys included Mg-4Al-1Ca, Mg-4Al-2Ca, Mg-4Al-3Ca, Mg-4Al-4Ca, Mg-5Al-3Ca, and Mg-6Al-3Ca. Constrained-rod casting was conducted with a steel mold. Rods were cast with their ends enlarged to act as anchors, which kept the rods from free contraction and thus induced tension in the rods to cause cracking during solidification. The susceptibility to hot cracking was evaluated based on both the widths and locations of cracks in the resultant castings. Both binary Mg-4Al and commercial alloy AZ91E, which is known to have a low susceptibility to hot cracking, were also included for comparison. It was found that within the composition range studied, the crack susceptibility decreased significantly with increasing Ca content (y) but did not change much with the Al content (x).
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Guan, Tian Yang, Zhi Feng Zhang, Min He, Yue Long Bai und Ping Wang. „Effects of Annular Electromagnetic Stirring Melt Treatment on Microstructure and Mechanical Properties of 7050 Rheo-Casting“. Solid State Phenomena 285 (Januar 2019): 219–23. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.219.
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The microstructure and mechanical properties of 7050 alloy rheo-castings after treated by Annular Electromagnetic Stirring (A-EMS) melt treatment were investigated. The results revealed that, under A-EMS, the refinement and homogeneity of the solidification structure could be improved greatly and the slurry was suitable for the following rheo-casting; and also the hot-cracking defects in the casting process were significantly alleviated, meanwhile, the strength and ductility of the alloy casting were found to be comparable to those of conventionally forged 7000 series alloys.
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Cao, G., und S. Kou. „Hot cracking of binary Mg–Al alloy castings“. Materials Science and Engineering: A 417, Nr. 1-2 (Februar 2006): 230–38. http://dx.doi.org/10.1016/j.msea.2005.10.050.
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Łyczkowska, K., J. Adamiec, R. Jachym und K. Kwieciński. „Properties of the Inconel 713 Alloy Within the High Temperature Brittleness Range“. Archives of Foundry Engineering 17, Nr. 4 (20.12.2017): 103–8. http://dx.doi.org/10.1515/afe-2017-0138.
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Abstract Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.
Dissertationen zum Thema "Cracking of castings"
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Jones, Eric Merwin. „Investigation of the stress corrosion cracking susceptibility of annealed and heat treated alloy 625 castings and forgings in sea water“. Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/10945/22324.
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The author hereby grants to the United States Navy, Wyman
Gordon, and M.I.T. permission to reproduce and distribute
copies of this thesis document in Whole or in part.Alloy 625, the nickel based superalloy commonly called Inconel* 625, was investigated for its susceptibility to stress corrosion cracking in sea water using the slow strain rate tensile test method. Four microstructures of the alloy commonly found in end products were investigated. Bimetallic couplings with other metals were simulated with a potentiostat at plus and minus one volt with respect to a saturated standard calomel electrode (SCE). Baseline tests were conducted in air and sea water without applied potential. The response of the alloy to cathodic protection of minus three volts SCE was also investigated on the two most commonly used microstructures, as cast" and "forged/annealed". The different microstructures developed were characterized with a scanning electron microscope (SEM). The gage lengths, fracture surfaces, and sections of test specimens were also examined with a SEM. The data from the slow strain rate tensile tests were compared with data from standard tensile tests performed on the same processed material. The results from this investigation indicate that Alloy 625 is not susceptible to stress corrosion cracking in the normal sea water service environment where temperatures are close to ambient. However, the results indicated that Alloy 625 is susceptible to the hydrogen embrittlement form of stress corrosion cracking when subjected to potentials that produce hydrogen evolution. This embrittlement leads to intergranular cracking.
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Lados, Diana Aida. „Fatigue crack growth mechanisms in Al-Si-Mg alloys“. Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0204104-125758.
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Thesis (Ph. D.)--Worcester Polytechnic Institute.Keywords: Microstructure; Elastic-Plastic Fracture Mechanics; Crack closure; A356; J-integral; Conventionally cast and SSM Al-Si-Mg alloys; Residual stress; Heat treatment; Fatigue crack growth mechanisms; Threshold stress intensity factor; Plastic zone; Paris law; Fracture toughness; Roughness. Includes bibliographical references.
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Kaněra, Miloš. „Výroba odlitků z austeniticko-feritických hyperduplexních korozivzdorných ocelích“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445174.
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The thesis deals with hyper duplex stainless austenitic-ferritic steels and their mechanical and castability properties. The evaluation of resistance to pitting corrosion is divided by PRE values. Steels with a PRE value higher than 48 belong to the group of hyper duplex steels. The theoretical part contains an introduction to the chemical composition, structure and properties of these steels. The practical part is focused on the conditions of tendency to crack castings during solidification and cooling. Furthermore, there is evaluated influence of intermetallic phases on mechanical properties.
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Lee, Kevin. „Understanding shell cracking during de-wax process in investment casting“. Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6783/.
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In investment casting, the removal of wax from the shell is a critical step which may cause shell failure. It would be advantageous to predict the stress development during de-waxing process with computer simulation. The process was simulated with the consideration of two aspects: (i) The thermo-physical data required to model the shell and wax behaviour in the autoclave environment and (ii) A simulation capable of capturing the interaction between shell, wax and the autoclave environment. Data on mechanical properties, thermal properties, permeability, rheology, thermal expansion and density was gathered for wax and shell as appropriate. Flow-3D was used to simulate the de-wax process such that the shell and wax can be simultaneously modelled. It was shown that the Von misses stress exceeded the expected critical failure stress at certain nodes after steam was introduced to the system. Waxes with higher viscosity were predicted to reach the critical stress sooner. The simulation showed that for the selected drainage orifice sizes that was no or little difference in the time taken to reach the critical stress. Wax compressibility which was considered to represent shell permeability was predicted to have a large effect on shell cracking prediction. In general, the statistics of failure in validation test limited the conclusions that could be drawn. Waxes predicted to show differences in cracking and drainage with increasing orifice size did so in the experiment. The simulated drainage times were greater than determined experimentally by around 380s and this requires further investigation.
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Fan, Jia Su. „An investigation of the cracking mechanism in continuous casting rolls during service /“. The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487684245467469.
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MILANI, CARLOS AUGUSTO RUPPENTHAL. „IDENTIFICATION AND SOLUTION OF HOT ROLLING CRACKING IN STRUCTURAL STEELS PROCESSED BY CONTINUOUS CASTING“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36911@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROO advento e consolidação do processo de lingotamento contínuo, hoje dominante no setor siderúrgico, trouxe à tona os crescentes esforços de investigação e análise dos fenômenos relacionados com o comportamento dos aços a elevadas temperaturas. Diferentemente do lingotamento convencional, o lingotamento contínuo é um processo dinâmico no qual ocorre a oscilação do molde enquanto o veio em solidificação é continuamente extraído ao mesmo tempo que é submetido a um segundo resfriamento dito secundário. No Brasil há um parque industrial de empresas que se dedicam à laminação a quente de semiacabados fornecidos por terceiros como placas de aço, as quais são cortadas a quente sob a forma de tarugos de seção quadrada que são então destinados a laminação. A linha de produção dessas empresas compreende basicamente produtos estruturais tais como barras chatas, barras redondas, barras quadradas, cantoneiras e até perfis especiais destinados à indústria automobilística e de máquinas. Uma série catastrófica de eventos de qualidade relacionados com trincas emergiu da laminação de tarugos de aço SAE 1020 oriundos de placas continuamente lingotadas. Essas trincas, porventura preexistentes ou latentes no interior das placas podem ter sido exacerbadas por efeitos de zonas termicamente afetas durante as operações de corte. A solução proposta para superação dessa contingência foi então a de criação de um aço de substituição com teores inferiores de carbono e maior conteúdo de ligas que preservasse as propriedades mecânicas do material laminado. Teores inferiores de carbono não apenas contribuem para a minimização dos efeitos oriundos das transformações peritéticas como também agem favoravelmente sobre as consequências decorrentes de zonas termicamente afetadas. Essa proposta foi bem sucedida e a composição química desse aço de substituição denominado pseudo-1020 passou a ser desde então padrão de laminação. Amostras do SAE 1020 laminado com ocorrências de trincas e do aço de substituição foram obtidas e transformadas em corpos de prova para a realização de ensaios de tração, dureza e impacto. Essa dissertação objetiva apresentar toda a fenomenologia relacionada com a ocorrência de trincas superfícies e internas em aços continuamente lingotados, em especial os submetidos a transformações peritéticas, e as premissas que fundamentaram a criação do aço de substituição e os resultados auferidos.
The advent and consolidation of the continuous casting process, currently dominant in the Steel Industry, raised the increasing investigation and analyses efforts on the phenomena related to the high-temperature behavior of the steels. Unlike the conventional ingot casting process, the continuous casting is a dynamic process in which occurs the mold oscillation while the strand under solidification is continuously withdrawn and submitted to a secondary cooling operation. In Brazil, it can be found an industrial park of companies dedicated to the hot rolling of semis supplied by third parties as steel slabs, which ones are flame cut in the form of square billets for rolling. The production mix of these companies encompasses structural steels such as flat bars, round bars, angles and even special profiles for the machines and automotive industries. A catastrophic series of quality events related to cracking emerged from the rolling of SAE 1020 billets made from continuously cast slabs. These cracks, perhaps pre-existing or latent in the inner parts of the slabs could be exacerbated by thermal affected zones during the flame-cut operations. The propose solution to overcoming this contingency was the creation of a replacement steel grade with lower carbon content and higher alloy content aiming to preserve the mechanical properties of the as rolled material. Lower carbon contents does not only contributes to the minimization of the effects arising from the peritetic transformations as also act in favor on the consequences coming from thermal affected zones. This proposition was well successful and the chemical composition of this replacement steel called pseudo- 1020 since then became a rolling standard. Samples of the rolled SAE 1020 steel with cracks occurrences and of the replacement steel were taken and transformed in specimens for tensile strengths, hardness and impact tests.This paper aims to present all related phenomena to the occurrence of inner and superficial cracks in continuously cast steels, in special the ones submitted to peritetic transformations, and the premises that support the creation of a replacement steel and the related results.
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Nilsson, Martin. „Thermal cracking of young concrete : partial coefficients, restraint effects and influence of casting joints“. Licentiate thesis, Luleå tekniska universitet, Byggkonstruktion och -produktion, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26358.
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Cracks can occur due to temperature induced movements during the hardening phase of concrete. Thermal cracks are not decisive for the load-bearing capacity but cause costs for repair and may reduce the life of the structure. The risk of cracking can be judged through safety values, (partial coefficients) given in building codes. In the thesis, partial coefficients for thermal cracking problems are determined with a probabilistic model. One crucial parameter influencing the risk of cracking is the restraint. In the report, methods are derived and presented for the determination of the restraint. Rotational boundary restraint from elastic foundations is treated as well as the restraint in internal points in the structures. For the determination of the rotational boundary restraint coefficient, applicable and simple graphical tools are presented. The restraint in internal points is based on a so-called plane-section restraint coefficient, a resilience factor for structures with length to height ratios smaller than seven, and a factor for slip failures in joints between the young and old parts. Four experiments of walls cast on slabs are presented in the thesis. On a precast slab, concrete walls are cast and loaded by restraint stresses induced by the temperature during the hydration. Different boundary restraint situations are used for the structure as well as different amount of reinforcement in the joint between the walls and the slab. The restraint and the amount of reinforcement are investigated regarding the risk of through cracking of the wall. The phenomenon of slip failure in joints has been shown in the tests.Godkänd; 2000; 20070318 (ysko)
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Amjadi, Cindy, und Justyna Melek. „The impact of stage casting on shrinkage restraint in concrete walls“. Thesis, KTH, Byggteknik och design, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279467.
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The most used widely material in the construction and industrial industry is concrete. Concrete is a material that has been used for a long time and will remain to do so. Therefore, it is especially important to obtain knowledge of the material’s properties and how it is affected by various conditions. A major problem with concrete is cracking that occurs when its shrinkage is prevented. When a concrete wall is cast against ground, shrinkage occurs. The cracks that develop due to this can cause leaks and reinforcement corrosion that not only reduces the lifespan of the concrete, but are also making it aesthetically ugly. One solution to reduce the restraint is to divide the casting into stages. This study contains investigation whether a thoughtful stage casting is a method that can theoretically and practically affect the shrinkage restraint and thereby the cracking in concrete walls. This report observes the tensile stresses in a 15 meter long concrete wall with strength class C30/37. The wall is exposed for two different relative humidity circumstances, indoor environment which gives 50% and outdoor environment which gives 80%. The analysis comprises four different casting methods for a wall; casting in one piece and three casting methods according to thoughtful stage casting. The contemplated time range between the casting stages is normal production time, 30 days, and extended production time, 60 days. At first the calculations for shrinkage and creep of the concrete had to be done according to Eurocode 2. The results from the calculations are thereafter used in the finite element program FEM-Design from the company Strusoft. The results in the report demonstrates the tensile stresses that arise in a 15 meter long wall without the stages and when the casting is done with thoughtful stages. A variation of the foundation depth consisting of non-cohesive soil is also presented for one of the casting methods. The conclusion of the results is that stage casting is a solution to reduce restraint and thereby stresses in concrete walls. The results reveal that the tensile stresses are reduced with the highest value of approximately 80%. The efficiency of casting into stages is possible and practicable within a normal production time.Det mest använda materialet i anläggnings- och industribranschen är betong. Betong är ett material som har använts länge och kommer fortsätta att användas. Därför är det främst viktigt att ha kunskap om materialets egenskaper och hur det påverkas av olika förhållanden. Ett stort problem med betong är sprickbildning när dess krympning förhindras. När en betongvägg gjuts mot ett underlag förekommer krymptvång. Sprickorna som uppstår på grund av detta kan orsaka läckage och armeringskorrosion som minskar betongens livslängd och är dessutom estetiskt fula. Ett sätt att minska tvånget är att dela in gjutningen i etapper. I detta arbete undersöks om en genomtänkt gjutetappsindelning är en metod som teoretiskt och praktiskt kan påverka krymptvånget och därmed sprickbildningen i betongväggar. Denna rapport betraktar dragspänningarna i en 15 meter lång betongvägg med hållfasthetsklassen C30/37. Väggen utsätts för två olika relativa luftfuktighetsförhållanden, inomhusmiljö samt utomhusmiljö vilket ger ett värde på 50% och 80%. Analyserna omfattar fyra olika gjutningsmetoder för väggen; gjutning utan etappindelning samt gjutning utförd enligt tre genomtänkta etappindelningar. Tiden som betraktas mellan gjutetappsindelningarna begränsas till normal produktionstid, 30 dagar, och en förlängd produktionstid, 60 dagar. Först utförs handberäkningar enligt Eurokod 2 på betongens krympning och krypning för att sedan sätta in resultaten i finita element programmet FEM-Design från Strusoft. Resultaten i rapporten redovisar de maximala dragspänningarna som uppstår i en 15 meter lång vägg utan etappindelning och då gjutning genomförs av genomtänkt etappindelning. Även en variation av friktionsjordens djup analyseras för en utav etappindelningarna. Slutsatsen av resultaten är att gjutetappindelning är en lösning till reduktion av tvång och därmed minskad spänning i betongväggar, då de maximala dragspänningarna reducerades med som högst ca 80%. Effektiviteten av gjutetappindelning är möjlig inom en normal utförandetid.
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Tanfener, Tugrul. „Finite Element Analyses Of Differential Shrinkage-induced Cracking In Centrifugally Cast Concrete Poles“. Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614847/index.pdf.
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Poles are used as an important constituent of transmission, distribution and communication structureshighway and street lighting systems and other various structural applications. Concrete is the main production material of the pole industry. Concrete is preferred to steel and wood due not only to environmental and economic reasons but also because of its high durability to environmental effects and relatively less frequent maintenance requirements. Centrifugal casting is the most preferred way of manufacturing concrete poles. However, misapplication of the method may lead to a significant reduction in strength and durability of the poles. Segregation of concrete mixture is a frequent problem of centrifugal casting. The segregated concrete within the pole cross-section possesses different physical properties. In particular, the shrinkage tendency of the inner concrete, where the cement paste is accumulated, becomes significantly larger. Differential shrinkage of hardened concrete across the pole section gives rise to the development of internal tensile stresses, which, in turn, results in longitudinal cracking along the poles. There is a vast literature on experimental studies of parameters affecting differential shrinkage of centrifugally cast poles. This research aims to computationally investigate the differential shrinkage-induced internal stress development and cracking of concrete poles. To this end, two and three-dimensional mathematical models of the poles are constructed and finite element analyses of these models are carried out for different scenarios. The computationally obtained results that favorably agree with the existing experimental data open the possibility to improve the centrifugal manufacturing technique by using computational tools.
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Kasvayee, Keivan Amiri. „On the deformation behavior and cracking of ductile iron; effect of microstructure“. Doctoral thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Material och tillverkning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-36852.
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This thesis focuses on the effect of microstructural variation on the mechanical properties and deformation behavior of ductile iron. To research and determine these effects, two grades of ductile iron, (i) GJS-500-7 and (ii) high silicon GJS-500-14, were cast in a geometry containing several plates with different section thicknesses in order to produce microstructural variation. Microstructural investigations as well as tensile and hardness tests were performed on the casting plates. The results revealed higher ferrite fraction, graphite particle count, and yield strength in the high silicon GJS-500-14 grade compared to the GJS-500-7 grade. To study the relationship between the microstructural variation and tensile behavior on macroscale, tensile stress-strain response was characterized using the Ludwigson equation. The obtained tensile properties were modeled, based on the microstructural characteristics, using multiple linear regression and analysis of variance (ANOVA). The models showed that silicon content, graphite particle count, ferrite fraction, and fraction of porosity are the major contributing factors that influence tensile behavior. The models were entered into a casting process simulation software, and the simulated microstructure and tensile properties were validated using the experimental data. This enabled the opportunity to predict tensile properties of cast components with similar microstructural characteristics. To investigate deformation behavior on micro-scale, a method was developed to quantitatively measure strain in the microstructure, utilizing the digital image correlation (DIC) technique together with in-situ tensile testing. In this method, a pit-etching procedure was developed to generate a random speckle pattern, enabling DIC strain measurement to be conducted in the matrix and the area between the graphite particles. The method was validated by benchmarking the measured yield strength with the material’s standard yield strength. The microstructural deformation behavior under tensile loading was characterized. During elastic deformation, strain mapping revealed a heterogeneous strain distribution in the microstructure, as well as shear bands that formed between graphite particles. The crack was initiated at the stress ranges in which a kink occurred in the tensile curve, indicating the dissipation of energy during both plastic deformation and crack initiation. A large amount of strain localization was measured at the onset of the micro-cracks on the strain maps. The micro-cracks were initiated at local strain levels higher than 2%, suggesting a threshold level of strain required for micro-crack initiation. A continuum Finite Element (FE) model containing a physical length scale was developed to predict strain on the microstructure of ductile iron. The material parameters for this model were calculated by optimization, utilizing the Ramberg-Osgood equation. The predicted strain maps were compared to the strain maps measured by DIC, both qualitatively and quantitatively. To a large extent, the strain maps were in agreement, resulting in the validation of the model on micro-scale. In order to perform a micro-scale characterization of dynamic deformation behavior, local strain distribution on the microstructure was studied by performing in-situ cyclic tests using a scanning electron microscope (SEM). A novel method, based on the focused ion beam (FIB) milling, was developed to generate a speckle pattern on the microstructure of the ferritic ductile iron (GJS-500-14 grade) to enable quantitative DIC strain measurement to be performed. The results showed that the maximum strain concentration occurred in the vicinity of the micro-cracks, particularly ahead of the micro-crack tip.Denna avhandling fokuserar på effekten av variationer i mikrostrukturen på mekaniska egenskaper och deformationsbeteende hos segjärn. För att undersöka dessa effekter, två olika sorter av segjärn, (i) GJS-500-7 och (ii) högkisellegerad GJS-500-14, gjutits till plattor av olika tjocklekar för att generera mikrostrukturvariationen. Mikrostrukturundersökning, samt drag- och hårdhetsprov gjordes på de gjutna plattorna. Resultaten visade att en högre ferritfraktion, grafitpartikelantal och sträckgräns i den högkisellegerade GJS-500-14-sorten jämfört med GJS-500-7. För att studera förhållandet mellan mikrostrukturell variation och spännings-töjningsbeteendet på makroskala, modellerades detta med hjälp av Ludwigson-ekvationen. De erhållna spännings-töjningsegenskaperna modellerades baserat på mikrostrukturell karaktäristika genom multipel linjärregression och variansanalys (ANOVA). Modellerna visade att kiselhalt, grafitpartikelantal, ferritfraktion och porfraktion var de viktigaste bidragande faktorerna. Modellerna implementerades i ett simuleringsprogram för gjutningsprocessen. Resultatet från simuleringen validerades med hjälp av experimentella data som inte ingick i underlaget för regressionsanalysen. Detta möjliggjorde att prediktera spännings-töjningsbeteendet och dess variation hos gjutna segjärns komponenter med liknande sammansättning och gjutna tjocklekar som användes i denna studie. För att kunna undersöka deformationsbeteendet på mikroskala utvecklades en metod för kvantitativ mätning av töjning i mikrostrukturen, genom DIC-tekniken (digital image correlation) tillsammans med in-situ dragprovning. I denna metod utvecklades en grop-etsningsprocess för att generera ett slumpvis prickmönster, vilket möjliggjorde DIC-töjningsmätning i matrisen och i området mellan grafitpartiklarna med tillräcklig upplösning. Metoden validerades genom benchmarking av den uppmätta sträckgränsen mot materialets makroskopiska sträckgräns mätt med konventionell dragprovning. Det mikrostrukturella deformationsbeteendet under dragbelastning karakteriserades. Under elastisk deformation avslöjade töjningsmönstret en heterogen töjningsfördelning i mikrostrukturen, och bildandet av skjuvband mellan grafitpartiklar. Sprickbildning initierades vid låg spänning och redan vid de spänningsnivåer som ligger vis ”knät” på dragprovningskurvan, vilket indikerar energidissipering genom både begynnande plastisk deformation och sprickbildning. Den lokala töjningen vis sprickinitiering skedde då den lokala töjningen översteg 2%, vilket indikerar att detta skulle kunna vara en tröskelnivå för den töjning som erfordras för initiering av mikro-sprickor. En kontinuum Finita Element (FE) modell utvecklades för att prediktera töjningen hos ett segjärn och dess fördelning i segjärns mikrostruktur. Materialparametrarna för denna modell optimerades genom att anpassa parametrarna i Ramberg-Osgood ekvationen. De predikterade töjningsfördelningarna jämfördes med de experimentell uppmätta töjningsmönstren uppmätta med DIC, både kvalitativt och kvantitativt. Töjningsmönstren överensstämde i stor utsträckning, vilket resulterade i att modellerna kunde anses vara validerade på mikronivå. För att kunna mäta töjningsmönster under dynamiska förlopp på mikronivå utvecklades en metod för att skapa prickmönster och att utföra in-situ CT provning i ett svepeletronmikroskop (SEM). Prickmönstret skapades genom avverkning med en fokuserad jonstråle (FIB), och provades på det ferritiska segjärnet (GJS-500-14 grad). Resultaten visade att maximal töjningskoncentration fanns i närheten av mikrosprickorna, framförallt framför sprickspetsen.
Bücher zum Thema "Cracking of castings"
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Jones, Eric Merwin. Investigation of the stress corrosion cracking susceptibility of annealed and heat treated alloy 625 castings and forgings in sea water. 1987.
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Bozorgi, Salar, Katharina Haberl, Christian Kneissl, Thomas Pabel und Peter Schumacher. „Effect of Alloying Elements (Magnesium and Copper) on Hot Cracking Susceptibility of AlSi7MgCu Alloys“. In Shape Casting, 113–20. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118062050.ch14.
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Eskin, D. G., M. Lalpoor und L. Katgerman. „Cold Cracking during Direct-chill Casting“. In Light Metals 2011, 667–74. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118061992.ch117.
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Eskin, D. G., M. Lalpoor und L. Katgerman. „Cold Cracking during Direct-Chill Casting“. In Essential Readings in Light Metals, 939–46. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118647783.ch119.
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Eskin, D. G., M. Lalpoor und L. Katgerman. „Cold Cracking During Direct-Chill Casting“. In Light Metals 2011, 669–74. Cham: Springer International Publishing, 2011. http://dx.doi.org/10.1007/978-3-319-48160-9_117.
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Eskin, D. G., M. Lalpoor und L. Katgerman. „Cold Cracking During Direct-Chill Casting“. In Essential Readings in Light Metals, 939–44. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48228-6_119.
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Zimmermann, Hans, Achim R. Büchner und Karl-Hermann Tacke. „Cracking Phenomena in Twin Roll Strip Casting of Steel“. In Steels and Materials for Power Plants, 29–32. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527606181.ch5.
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Manohar, P. A. „Stress Corrosion Cracking Failure of Jackbolts for Die Casting Press“. In THERMEC 2006, 2162–67. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.2162.
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Pérez Caldentey, Alejandro, Luigino Dezi, Javier Jordán, Graziano Leoni, Gianluca Ranzi und Raymond Ian Gilbert. „Case studies considering the influence of the time-dependent behaviour of concrete on the serviceability limit state design of composite steel-concrete bridges“. In Time-dependent behaviour and design of composite steel-concrete structures, 157–88. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/sed018.ch8.
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<p>This chapter introduces three case studies that describe how aspects related to the serviceability limit state design associated with the time-dependent behaviour of concrete can be considered in a design situation. The first case study considers the Oxec II Bridge in Guatemala. It provides an overview of the stress verification of the steel section of the composite bridge and accounts for concrete time effects to capture the stress redistribution that occurs between the concrete and the steel components. The second case study deals with the Yalquincha Viaduct in Chile and provides an overview of the type of long-term analyses that can be carried out when considering the influence of different cross-sectional arrangements on the time-dependent response of the bridge. The last case study focusses on the Serra Cazzola Viaduct in Italy and highlights the opportunities available to designers in exploiting optimised casting sequences to reduce the time-dependent stresses induced in the concrete and, therefore, mitigate the likelihood of concrete cracking.</p>
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Katgerman, L. „A Mathematical Model for Hot Cracking of Aluminium Alloys during DC Casting“. In Essential Readings in Light Metals, 907–11. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118647783.ch114.
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Katgerman, L. „A Mathematical Model for Hot Cracking of Aluminium Alloys During D.C. Casting“. In Essential Readings in Light Metals, 907–11. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48228-6_114.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Cracking of castings"
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Jones, Kerry, Matt DeGeorge und Monique Stewart. „Improved Truck Castings“. In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6231.
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This paper examines alternative, improved materials for truck castings. The first part looks at steels that would not require post-weld heat treatment after repair welding. The second part investigates specific applications for temperatures below −50 °F. The rapid, dramatic temperature changes that occur during welding can form brittle phases or cracking in some steels. The weld has three areas of differing structure: the weld, the heat affected zone (HAZ), and the parent metal. The maximum hardness occurs in the HAZ and is the limiting factor in determining weldability. An ultraweldable steel is a steel that does not require post-weld heat treatment. Many steels were evaluated for their chemical composition and susceptibility to cracking; those that were likely to form brittle phases were eliminated from consideration. Four low alloy steels and one carbon steel were selected as being potentially ultraweldable. To evaluate the ultraweldability of these steels, groove welds and two types of spot welds were made on the five candidate alloys. The welds were then sectioned and prepared for microstructural and microhardness evaluation. Microhardness readings were taken across the weld, spanning the weld, HAZ, and base material. Three of the steels formed hard, brittle phases during most of the tests. This indicates these materials are not ultraweldable. Two of the low alloy steels did meet the requirements for ultraweldability. Future work in this area would include producing truck castings from these materials. At low temperatures, plain carbon steels, such as the types used in truck castings, can fracture in a brittle manner, with no visible deformation. The material property of deforming without fracture is toughness or ductility. Using materials that retain their toughness in low temperatures could prevent brittle failures of truck castings. Six grades of steel currently used in low temperature applications were selected for this research. Specimens from each of the six materials were evaluated for tensile properties at multiple temperatures. Charpy impact specimens were tested at temperatures ranging from −20 °F to −120 °F. The measured room temperature tensile properties of each of the six steels met or exceeded the requirements for Grade B+, the steel currently used for truck castings. Four of the steels showed impact energies far above that of the current Grade B+, but two of them gave consistently higher impact energies than all others. These would be the best candidates for future work in this area. Future work would involve producing full size truck castings from one or more of these alloys, then testing them for fatigue performance, preferably at low temperatures.
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Bernstein, Henry L., R. Craig McClung, T. R. Sharron und James M. Allen. „Analysis of General Electric Model 7001 First Stage Nozzle Cracking“. In ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-311.
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Analyses of first stage nozzle cracking in General Electric Model 7001B and 7001E industrial gas turbines are presented. Empirical algorithms are developed to predict the maximum extent of cracking that is visible on these nozzles as a function of engine cyclic history and the number of fired hours. It is shown that the algorithms predict this cracking to within a factor of two. Metallurgical analyses of nozzles show that crack growth follows the carbide-matrix interface, environmental attack occurs at the crack tip, and that the microstructure changes by increasing the amount of carbide precipitation which increases the hardness. These metallurgical results, along with mechanical test data and stress analyses from the literature, are used to understand the nature of nozzle cracking. The maximum extent of cracking coincides with locations of maximum thermal stresses as determined by finite element analyses of similar nozzle designs. This location is at the airfoil-shroud junction on the middle vanes of multi-vane castings. The use of these algorithms as a predictive maintenance tool and the ability to visually inspect nozzles in the engine also are discussed.
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Harris, Ken, und Jacqueline B. Wahl. „CM 939 Weldable® Alloy“. In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53966.
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IN 939 alloy, developed by the International Nickel Co. in the late 1960s, is a unique 22% Cr hot corrosion resistant γ′ strengthened, cast nickel-base superalloy. It is widely used in industrial gas turbines for equiaxed vanes, vane segments and burner nozzles and is of interest to the aero turbine industry for LP and PT integral nozzles (vane rings) and high temperature turbine casings. However, IN 939 is considered difficult to weld repair without parent metal microcracking and can exhibit marginal ductility in heavy section castings. Cannon-Muskegon has developed a proprietary chemistry modified version of IN 939 alloy designated CM 939 Weldable®. Emphasis has been directed on optimizing aim chemistry and ultra high purity manufacture using CM-developed single crystal superalloy melting and raw material technology and subsequently on obtaining superior casting microstructure for improved weldability and mechanical properties. Alloy purity and heat cleanliness will be discussed, along with a simplified two-step heat treatment cycle, resulting in attractive microstructure, mechanical properties and repair weldability. Significant market interest has resulted in extensive vacuum casting experience throughout the gas turbine industry. Excellent results in terms of fluidity, casting cleanliness and minimal microporosity have been obtained without any hot tearing or hot cracking problems.
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Savic, Adrijana, B. Terry Beck, Aaron A. Robertson, Robert J. Peterman, Jeremiah Clark und Chih-Hang (John) Wu. „Effects of Cover, Compressive Strength, and Wire Type on Bond Performance in Prismatic Prestressed Concrete Members“. In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6153.
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The bond between wire and concrete is crucial for transferring the stresses between the two materials in a prestressed concrete member. Furthermore, bond can be affected by such variables as thickness of concrete cover, type of pre-stressing (typically indented) wire used, compressive (release) strength of the concrete, and concrete mix. This work presents current progress toward the development of a testing procedure to get a clear picture of how all these parameters can ruin the bond and result in splitting. The objective is to develop a qualification test procedure to proof-test new or existing combinations of pre-stressing wire and concrete mix to ensure a reliable result. This is particularly crucial in the concrete railroad crosstie industry, where incompatible conditions can result in cracking and even tie failure. The goal is to develop the capability to readily identify compatible wire/concrete designs “in-plant” before the ties are manufactured, thereby eliminating the likelihood that defectively manufactured ties will lead to in-track tie failures due to splitting. The tests presented here were conducted on pre-tensioned concrete prisms cast in metal frames. Three beams (prismatic members) with different cross sections were cast simultaneously in series. Four pre-stressing wires were symmetrically embedded into each concrete prism, resulting in a common wire spacing of 2.0 inches. The prisms were 59.5in long with square cross sections. The first prism was 3.5 × 3.5in with cover 0.75in, the second was 3.25 × 3.25in with cover 0.625in and the third prism in series was 3.0 × 3.0 in with cover 0.50in. All pre-stressing wires used in these initial tests were of 5.32 mm diameter and were of the same wire type (indent pattern) denoted by “WE”, which had a spiral-shaped geometry. This is one of several wire types that are the subject of the current splitting propensity investigation. Others wire types include variations of the classical chevron shape, and the extreme case of smooth wire with no indentions. The wires were initially tensioned to 7000 pounds (31.14 KN) and then gradually de-tensioned after reaching the desired compressive strength. The different compressive (release strength) strength levels tested included 3500 psi (24.13 MPa), 4500psi (31.03 MPa), 6000 psi (41.37 MPa) and 12000psi (82.74MPa). A consistent concrete mix with water-cement ratio 0.38 was used for all castings. Geometrical and mechanical properties of test prisms were representative of actual prestressed concrete crossties used in the railroad industry. Each prism provided a sample of eight different and approximately independent splitting tests of concrete cover (four wire cover tests on each end) for a given release strength. After de-tensioning, all cracks that appeared on the prisms were marked, and photographs of all prism end surfaces were taken to identify the cracking field. During the test procedure longitudinal surface strain profiles, along with live-end and dead-end transfer lengths, were also measured using an automated Laser-Speckle Imaging (LSI) system developed by the authors. Both quantitative and qualitative assessment of cracking behavior is presented as a function of cover and release strength. In addition to the identification of whether cracking took place at each wire end location, measurements of crack length and crack area are also presented for the given WE wire type. The influence of concrete cover and release strength are clearly indicated from these initial tests. The influence of indented wire type (indent geometry) will also be discussed in this paper, along with a presentation of some preliminary test results. This work represents a successful first step in the development of a qualification test for validating a given combination of wire type, concrete cover, and release strength to improve the reliability of concrete railroad crosstie manufacturing.
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Heo, Hyeonu, Addis Tessema, Shaheer Iqbal, Jaehyung Ju und Addis Kidane. „Thermal Stress Analysis of Gypsum Shell Cracking in Polyjet-Based Rapid Casting of Cellular Metals“. In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52417.
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Cellular (or lattice) metals are increasingly gaining attention for their having combinations of mechanical, thermal, and acoustic properties that provide potential opportunities for diverse multifunctional structural implementations. These include ultra-light structures with high specific strength and high specific strain, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. The emerging 3D printing technologies including direct and indirect additive manufacturing processes may accelerate the realization of their structural applications of cellular metals. For indirect additive manufacturing processes, sacrificial patterns are 3D printed with castable polymers, followed by metal filling into a mold cavity to make final cellular metals. With a high stiffness of a castable polymer, e.g., VisiJet® Procast, it is possible to build network lattice cellular structures, replacing wax which has been used for traditional investment casting processes. In general, a high thermal stress is expected during burning-out process of the rapid casing. Due to the castable polymer’s new properties, no literature is available on thermal stress between the castable polymer and ceramic shells for indirect additive manufacturing of cellular structures. The objective of this study is to investigate i) thermal stress by thermal expansion mismatch between a sacrificial pattern made of a castable polymer and a coated gypsum shell and ii) an effect of the thickness of the coated gypsum shell on thermal cracking. Starting with thermal analysis, glass transition temperature, melting temperature and thermal expansion coefficient are obtained from experiments. An analytical model for thermal stress analysis is constructed with thermo-mechanical constitutive equations and compatibility equations, followed by a failure analysis at the coated shells where gypsum is used for coating the sacrificial pattern. The thermo-mechanical analysis is conducted as a function of temperature and coated shell thickness followed by a numerical validation with a finite element (FE) based simulation. The castable polymer has the potential to be used as a base material for manufacturing 3D network cellular sacrificial patterns with thin cell walls over conventional wax materials due to its high modulus and low thermal expansion coefficient during the burning out process of the sacrificial pattern.
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Gra˚berg, Stig, Lars Volden und Anthonius Johannes Paauw. „Mid Thickness Delayed Cracking of Z-Quality Offshore Steel“. In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49003.
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During fabrication of a steel structure for an offshore modification project, delayed cracking was experienced in the mid plane or centre line of a 30 mm thick plate. The plate was part of a restraint box frame where 25 mm plates were welded to this 30 mm plate on both plate-surfaces. The applied 30 mm plate was a higher strength offshore steel (EN10225-S420 G2+M), with special through thickness properties and enhanced chemical composition as defined in material data sheet MDS Y30 of NORSOK M-120. Fracture mechanical testing including KV and CTOD in the mid plane confirmed that a very low toughness was present here with a brittle fracture type (cleavage). The plate was manufactured by the continuous casting process which due to centre line segregation resulted in high levels of manganese sulfide inclusions but also niobium carbides/nitrides. The plate manufacturer considered the documented toughness level as expected. Similar testing was performed on a 30 mm plate also delivered to the same material specification but of which the material certificate revealed a 10 times lower sulfur and phosphorus content indicating a much higher steel refinement. A significant higher toughness was obtained for this steel with high ductile behavior. Both steels showed a similar through thickness ductility, measured elongation for the through thickness tensile specimen, which implies that this property does not guaranty for the observed material behavior.
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Suyitno, L. Katgerman und A. Burghardt. „Determination of Boundary Conditions During the Start-Up of DC Casting“. In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33830.
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The start-up phase of DC (direct chill) casting of aluminium alloys is a critical stage during which unwanted phenomena can occur, for example: butt curl, ingot cracking, and re-melting. To avoid these problems, simulation of the DC casting process during this phase is very important. However, the simulation task is not an easy job, because the boundary conditions to be applied are not easily defined and established. To define the boundary condition inverse methods are used in combination with experimental data. The aim of the simulations is intended to predict butt curl and butt temperatures. By application of inversely determined boundary conditions, results can be obtained that correlate well to measured data, even for different casting practices.
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Shiga, Keisuke, Yasuhiro Hara und Eiichi Yamamoto. „Repair Welding of Long-Term Used Ethylene Pyrolysis Radiant Tubes“. In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61904.
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Ethylene pyrolysis furnace radiant tubes have been used at the highest temperature in petrochemical plants. Although the tubes suffer several damages, carburization is the most important one which causes of the tube replacement. Carburization reduces the weldability and causes cracking at repair welding. This paper describes the degradation phenomena and the weldability of long-term used centrifugal casting tubes at the ethylene pyrolysis furnace.
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Kobayashi, Kenji, Tomohiko Omura, Masahiko Hamada, Hiroyuki Nagayama, Izuru Minato und Yuki Nishi. „Full Ring Evaluation of X70 Grade UOE Line Pipes for Sour Service“. In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90417.
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High-strength large-diameter UOE line pipes over X70 grade are difficult to apply to actual fields, including H2S, because of a deterioration of sour resistance and a lack of past performance. However, API X70 grade large-diameter UOE line pipes for sour service have been manufactured stably by optimizing the continuous casting process, controlling the shape of inclusions and decreasing coarse precipitates. A full-ring test can simulate fairly well the actual applied conditions of line pipes and evaluate hydrogen induced cracking (HIC), sulfide stress cracking (SSC) and stress oriented hydrogen induced cracking (SOHIC) of line pipes for sour service simultaneously. It was confirmed that the X70 grade UOE line pipes have a good sour resistance from standard HIC tests, four-point bent beam SSC tests and the full-ring test including a seam weld under severe sour conditions (NACE solution A with 0.1 MPa H2S). In addition, the SSC resistance of a girth welded portion was also investigated by using simulated HAZ.
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Russo Spena, Pasquale, Manuela De Maddis und Franco Lombardi. „Influence of Microstructure on Crack Susceptibility of Large Chilled Iron Mill Rolls“. In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89436.
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Large chilled iron mill rolls fabricated by permanent-mold gravity suffer from surface macroscopic cracking during iron solidification. This defect is usually intermittent over time, and in some extent, unrelated with the chemical composition and the process parameters used. To study this phenomenon, a metallographic analysis has been carried out on two real 5.5-ton chilled iron mill rolls made of the same chemical composition, manufactured with quite similar process parameters, but giving two very different results in practice: one of the two mill rolls exhibited a macroscopic crack. Because of the different metallurgical structures observed, especially regarding graphite content, a three-dimensional (3D) numerical analysis has been adopted to predict the thermal-mechanical behavior of the casting during the solidification and cooling stages. Special attention has been dedicated to the influence of the graphite expansion on mechanical stresses occurring in the casting skin. Numerical results point out that graphite expansion notably affects the evolution of stress-strain fields within the casting to an extent that it could lead to the formation of macroscopic cracks in the early stages of the casting solidification. Furthermore, the numerical analysis highlights that the thermal deformation of the permanent mold contributes to increase the risk of cracks to occur.
Berichte der Organisationen zum Thema "Cracking of castings"
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Richards, Von. FInal Report - Investment Casting Shell Cracking. Office of Scientific and Technical Information (OSTI), Dezember 2003. http://dx.doi.org/10.2172/819623.
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Das, Subodh K. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking. Office of Scientific and Technical Information (OSTI), Januar 2006. http://dx.doi.org/10.2172/862129.
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Das, S. K., S. Ningileri, Z. Long, K. Saito, M. Khraisheh, M. H. Hassan, K. Kuwana et al. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking. Office of Scientific and Technical Information (OSTI), August 2006. http://dx.doi.org/10.2172/940314.
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